Page/Post won't Publish/Update with the word 'exit' in the content editor

[ldekay]

We were trying to edit/update a page created a few upgrades ago but it wouldn't update... kept returning "Page Not Found". Tried creating a new page with the same text, same result when I tried to Publish.

Began eliminating sections and was able to Update. Then began eliminating words within that section and finally found that removing or changing the word 'exit' was the key.

replaced 'exit' with 'get out of' and 'escape' in last paragraph of ​http://whitesalmonschools.net/ecar/compose-an-effective-post/

[SergeyBiryukov]

Could not reproduce on a clean install.

The "exit" word appears to trigger some overzealous security rule on your server. Please try the support forums for troubleshooting: ​http://wordpress.org/support/.

[GaryJ]

Couldn't reproduce on an existing install (but currently 3.7-beta2) either.

[carambamoreno]

I have this same error. I am on wordpress 4.9 with the Twenty Seventeen theme installed, every plugin is uninstalled and including the word exit shows a 403 error.

The error doesn't happen when the word exit is not present.

I have reset permalinks and checked for files and folders permissions.

[welcher]

Could not reproduce in 4.9 or current trunk.